Mole Concept
Chemistry · मोल संकल्पना
📋Quick Overview
A mole is a unit to count atoms, molecules, or particles — just like a 'dozen' means 12 items. One mole = 6.022 × 10²³ particles. This number is called Avogadro's Number (Nₐ), named after Italian scientist Amedeo Avogadro. The mole concept helps us connect the microscopic world (atoms) with the macroscopic world (grams we can weigh).
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Avogadro's Number: Nₐ = 6.022 × 10²³ — This is the number of particles in exactly ONE MOLE of any substance
📖Key Definitions & Formulas
| Term | Definition | Formula / Value |
|---|---|---|
| Mole | Amount of substance containing 6.022×10²³ particles | 1 mol = 6.022×10²³ particles |
| Molar Mass | Mass of 1 mole of substance in grams | Molar mass = Atomic/Molecular mass in grams |
| Number of moles | n = Given mass / Molar mass | n = m / M |
| Number of particles | N = n × Nₐ | N = (m/M) × 6.022×10²³ |
| Molar Volume (STP) | Volume of 1 mole of any gas at STP | 22.4 litres at STP |
📖Molar Mass Examples
| Substance | Formula | Calculation | Molar Mass |
|---|---|---|---|
| Water | H₂O | 2(1) + 16 = 18 | 18 g/mol |
| Carbon dioxide | CO₂ | 12 + 2(16) = 44 | 44 g/mol |
| Sulphuric acid | H₂SO₄ | 2(1) + 32 + 4(16) = 98 | 98 g/mol |
| Sodium chloride | NaCl | 23 + 35.5 = 58.5 | 58.5 g/mol |
| Glucose | C₆H₁₂O₆ | 6(12)+12(1)+6(16) = 180 | 180 g/mol |
📖Empirical vs Molecular Formula
📖Avogadro's Law (for gases)
- •Equal volumes of all gases at same temperature and pressure contain equal number of molecules
- •At STP (0°C, 1 atm): 1 mole of any gas occupies 22.4 litres
- •STP = Standard Temperature and Pressure (0°C = 273K, 1 atm)